Tetrasaccharides

Stachyose is a tetrasaccharide consisting of two α--galactose units, one α--glucose unit, and one β--fructose unit sequentially linked as Gal(α1→6)Gal(α1→6)Glc(α1↔2β)Fruf. Together with related oligosaccharides such as raffinose, stachyose occurs naturally in numerous vegetables (e.g. green beans, soybeans and other beans) and other plants.

Carbohydrate antigen 19-9 (CA19-9), also known as sialyl-LewisA, is a tetrasaccharide which is usually attached to O-glycans on the surface of cells. It is known to play a role in cell-to-cell recognition processes. It is also a tumor marker used primarily in the management of pancreatic cancer.

thumb|Chemical structure of stachyose A tetrasaccharide is a carbohydrate which gives upon hydrolysis four molecules of the same or different monosaccharides. For example, stachyose upon hydrolysis gives one molecule each of glucose and fructose and two molecules of galactose. The general formula of a tetrasaccharide is typically C24H42O21.

chemical compound